Annoyed part of orchestra served up very loud song (7,3)
I believe the answer is:
brassed off
'annoyed' is the definition.
'part of orchestra served up very loud song' is the wordplay.
'part of orchestra' becomes 'brass' (I've seen this before).
'served up' says the letters should be written in reverse.
'very loud' becomes 'ff' (musical abbreviation).
'song' becomes 'ode'.
'ff'+'ode'='ffode'
'ffode' back-to-front is 'edoff'.
'brass'+'edoff'='BRASSED OFF'
(Other definitions for brassed off that I've seen before include "Fed up" , "Exasperated" .)